And what exactly does that have to do with math?

Thanks for this... seems odd that a magic damage spell can crit. Last Cho-gath game I souped up to 120 armor pretty quick then got crit for 450 and was like "wtf?" ... still had a MR of around 25 at the time. Now I get it

TYVM!

Ah... thank you. I didn't even stop to think about that. I tested most of this stuff on neutrals. Thank you! I will correct myself in earlier posts.

You're an idiot if you think you can look at a person's record without any idea what went on in a game with his teammates (and the other team, for that matter), and judge a person's skill with a champion. Want to know how many of those games I lost to champions badly in need of a nerf? Four. Also check out the defeats where I still held a positive score on the losing team. Pirate doesn't win games alone. He is not a carry, I can guarantee you that. I get so many game where there is no tank or no carry on my team... or the carry sucks. I play it out anyways and always do my job as pirate. You can't see any of that sh*t looking at my "recently played" tab, so screw off.

For the record to everyone reading this, my summoner is level 30, and I have hit the point where my ELO matches me up against tough opponents, such that rather than winning 10 games in a row, like I could at level 7, I now win about 50% of my games, which is what's supposed to happen if the rating system is perfect. Everyone goes on losing streaks, but whatever. Take the advice in this thread, or continue playing whatever sh*tty way you prefer. Hopefully I will meet you in game sometime and wreck your sh*t.

And like Niles said, what does this have to do with math? Does it sound like I know what I'm talking about? It's probably because I'm right, and it's why you got excited about this thread to begin with.

Sorc Boots convinces me. Haunting Guise does not.

I'd rather have the 18% crit chance from an Agility Cloak or Phage to start a Trinity Force.

Now, I use only Quints and Marks for my crit damage, giving me +34%. I also run a 9/0/21 mastery build, like you. The Agility Cloak would increase my DPS far better than the Haunting Guise will and for a much cheaper price. Even with base crit damage, I wouldn't expect that much more damage on even a sub-40 MR target and it would have superior damage in almost every other MR situation, given the prevalence of Merc Treads.

The damage increase from his ult shouldn't be enough to offset this.

I should mention that if my opponents remain at 30 resist, I won't upgrade to sorc boots until they get more magic resist. You can put that 750 gold towards sheen or, agility cloak, if that is what you prefer. Having the extra cooldown helps significantly in letting you parrrley more and remove scurvy more, especially when you factor in the 9% cooldown reduction that you and I get with our 9/0/21 mastery build. Also after pushing and retreating, it is possible to have cannon barrage up and ready again in case the enemy decides to chase us.

You must also consider that more skilled players will have magic reduction runes in their build.

If you must take one or the other, I would take haunting guise over sorc boots for the extra cooldown and early game hp/mana regen it provides while in lane. Sorc boots only gives you magic penetration, haunting guise gives you magic penetration, mana regen for more parrrley, hp regen, and cooldown reduction for not much more cost. The extra movespeed from sorc boots is about the same as just having level 5 raise moral.

TL,DR
Take haunting guise over sorc boots if you only want one magic pen item.

Have you tried Lich Bane and stacking AP items? I did some minor tests and it seemed it didn't do nearly as much as Sheen for some reason.

Could you explain why it doesn't work as well?

On the flip side, this implies that you're rushing Haunting Guise before Sheen. Even at the maximum 20% damage increase, it pales in comparison to Sheen. In exchange, you're getting mana regen and HP regen. With only the support tree regen and Sheen, I normally have sufficient mana for most situations. Personally, even though the actual % increase of damage from magic penetration is greater early on, the amount of damage being multiplied is lower. I'd much rather get Sorc Boots after I complete my Trinity Force.

By removing Haunting Guise from the build, it's a net loss of a maximum of 20% damage, assuming the enemy has 40 MR or less. Given how many people are packing MR runes and Aegis of Legion, this is an optimistic estimate.

In my eyes, Sorc Boots is the superior magic penetration item, if you only want one. As you say, it grants great move speed (never mind that pirate can break 470 move speed with boots 1) and penetration for Parrley at minimal cost.

1337 is simply too high of a price to justify magic penetration on Parrley.

It will do less if you have less AP than attack damage.

Most likely because if you're stacking AP, you aren't stacking attack items, and Gangplank's base attack is one of the main components of Parrrley's damage. Sheen uses base attack damage as well.